Diversion valve and system



States en [72] Inventors Robert Barclay Beahm, Brighton; 3,084,6744/1963 Watson 137/609X William B. Brosius, Jr., Perinton; Bruce FOREIGNPATENTS Gibsml, Greece; Leavi"; 1,174 725 11/1958 France 137/608Brighton, New York P E J K Ch 21 A L No g.' rrmary xammerames ee 1 1 Ezf our, 1967 AtlrneysPeter J. Young, Jr. and Joseph C. Mac Kenzle [45]Patented Oct. 6, 1970 1 Asslgnee Sybmn cofporatlon ABSTRACT: A diversionvalve consists essentially of a pair of a corporatlon of New Yorkthree-way valves which are connected together at right angles to eachother. Liquid entering the end of one valve and exiting [54] DIVERSIONVALVE AND SYSTEM out the other would move in a flow path at right anglesto a correspondlng flow in the other. However, a common duct to- 17Claims, 6 Drawmg Figs.

terconnects portions of such flow paths. The one valve 1s ar- U-S.ranged its flow path horizontal and is upplied in. 137/612-1 termediateits liquid flow path, which liquid either goes out Int. one end or theother of the valve one uch end i onne ted Fwd 3/00 by the common duct tothe intermediate portion of the other [50] Field ofSearch 137/608,valve's fl path, which is vertically Urieme Hence, liquid 6091 612-1,312 comes out one end of the latter valve or the other. The com- 56 R fC1 d mon duct slopes down from the horizontal valve to the vertical l eerences I e valve. The stem of the one valve extends horizontallythrough UNITED STATES PATENTS a stuffing box which is mainly an O-ringsealed cylindrical 228,051 5/1880 Fowler 137/608 passage through themetal body of the valve. The outer end of 1,624,572 4/1927 Bagby137/609X the stuffing box supports a snugly fitting fluid-perviousTeflon 2,484,622 /1949 Hartman 137/312 guide for the stem, and the stemis hard chrome plated where 3,052,444 9/1962 Kintner 137/612.1X itcontacts the stuffing box which prevents galling, and pro- 3.054,4239/1962 'l-loule 137/609 vides wear-resistance.

FORWARD DI VERY Z 4t 1% 30 P 5 I25 19 2/ I4 10 893 6 7 26 f FWD 1 3!011/ 1 I02 /3 I07 28 30 1% I26 EAK Sheet 3 H: q NV .93 nv I -N\ m I I 9.9. RV mm ow mm nv fm R 0 km 3 .n m ....L ..III.\\\\\ a f Ill u 1% nDIVERSION VALVE AND SYSTEM In flow diversion valve systems, multi-wayvalving allows transferring liquid from one place to another and, onoccasion, diverting it to still another place. Where healthconsiderations are involved, as in pasteurizing milk, sanitaryregulations promulgated by public health authorities impose variousconsiderations on the design of the system, such as leak detection andprotection, self-drainability and cleanability.

The first consideration leads to valve designs wherein it is sought tomake leakage visible from the exterior of the system, and to isolateleaked liquid from the system. The second consideration is obviouslyrelated to the first, and involves so constructing the parts of thevalving touched by the milk, and so orienting the valving, that if milkis not supplied to the valve, milk previously suppliedto the valvedrains out of it under the force of gravity. The third considerationranges from making the valving easily disassemblable for cleaning, tomaking its parts cleanable in place, i.e., without dissasembly, by whatamounts to circulating cleaning and sanitizing agents in the system,instead of milk.

The patents to Newhall, Karst and Hartman, US. Pat. Nos. 2,118,858,2,243,344 and 2,484,622, respectively, represent past approaches toproviding sanitary type valving for pasteurizing systems. Theconsiderations referred to above are reflected in the valve design ofthese patents. Thus, interiors of these valves are provided with smoothsurfaces oriented for drainage to low points; and threads, crevices andother possible collectors of liquid are shunned. The present inventionalso relies on such expedients, but in contrast to the patent devices,provides substantially total drainability, leak detection andprotection, and is truly cleanable in place. In substance, the inventionamounts to providing a pair of valves, like those of the patents (butomitting mechanical leak detector elements), orienting the valves atright angles to one another, and interconnecting the valves such thatdrainage from both valves flows to the same outlet, which is part of oneof the valves.

In the drawings:

FIG. I is a partly schematic, partly crosssectional showing of adiversion valve system according to the invention;

FIG. 1A is a fragment illustrating an operational condition of thesystem of FIG. 1;

FIGS. 2 and 3 are elevations, partly in section, of a specificconstruction of valving according to the invention;

FIG. 4 is a plan view of a detail of FIG. 2; and

FIG. 5 is a perspective view of the diversion valve according to theinvention.

In FIG. 1, a flow diversion valve according to the invention essentiallyconsists of a pair of like three-way valves H and V. Each valve is madeof suitable material, such as stainless steel, and its interior partsare smooth-surfaced, crevice-free, thread'free, and their surfaces areso sloped and contoured that, in the illustrated orientation, liquid inthe valve drains by gravity, to some place where it can exit from thevalve under the force of gravity. Each of valves H and V are in essencedesigned in accordance with prior art teachings in these respects.However, it is to be noted that the valve according to the inventionneither has nor needs distinct leak detector elements of the sortdescribed in connection with FIG. 3 of the Hartman patent.

Looking at valve H in detail (no separate description will be made ofvalve V, since its parts are the same), valve H includes a fluid conduit1, having a valve chamber 2, the interior of which latter is providedwith a pair of beveled surfaces providing seats 3 and 4, between whichvalve plug 5. having correspondingly-beveled discs 6 and 7 moves.Conduit l includes a portion 8, through which a valve stem 9 passes,extending into chamber 2 and having discs 6 and 7 fixed thereto. Theparts thus far referred to have circular contours, which are coaxialwith the line of motion of stem 9, the section portrayed in FIG. 1 beingon the diameters of the part contours. The stem 9 passes through astuffing box portion 10 of the por tion 8, and has an extension 11 fixedthereto by a coupler I2 which permits a motor 13 of valve H to beremoved therefrom. The motor 13 is mounted by a rigid bracket 14 on thegland portion 10 of the valve and includes a flexible diaphragm 15,fixed to the extension 11 and closing off an air dome l6 fixed tobracket 14. Dome 16 has a gland portion 17, through which extension 11passes, and, by means of a plate 18 fixed to the end of the extension11, is forced toward the left (in the drawing) by a spring 19 compressedbetween said plate and said dome. An air line 20 is connected at one endto the closed chamber 21 defined by dome l6 and diaphragm l5, and itsother to a valve 22. For purposes of explanation, valve 22 is to bedeemed a three-way valve, which as shown, opens the interior of chamber21 to the atmosphere via a vent 23 and air line 20.

Valve 22 can also be made to connect the air line 20 to an intake 24 ofthe valve 22 which is connected to a source of air (designated AIRSUPPLY) under pressure greater than atmosphere, this condition of valve22 being illustrated in FIG. 1A.

It will be evident that in FIG. I, the spring 19 forces stem 9 to theleft, thereby seating disc 6 in seat 3, and sealing the in terior ofportion 8 from the interior of portion 2. On the other hand, with valve22 in the condition shown in FIG. 1A, the air pressure from the airsupply enters chamber 21 and forces diaphragm l5 and, hence, stem 9,also, to the right, thereby unseating disc 6 from seat 3 and seatingdisc 7 in seat 4, thus allowing the interiors of portions 8 and 2 tocommunicate freely.

The valve H has an inlet 25 opening through the side of portion 2 intothe interior thereof between seats 3 and 4. An outlet 26, essentially arightward extension of portion 2, provides for flow between whatever isconnected to the right end of outlet 26 and the interior of extension 2,and past seat 4, whenever the disc 7 is unseated as shown in FIG. 1. Anoutlet 27 performs the same function with respect to flow via seat 3between the interiors of portions 2 and. 8. According to the invcntion,the interior outlet 27 connects to the lowest point in the interior ofportion 8, and from there extends downwardly as the common conduit 28,of which the lowest interior points monotonically slope downwardly awayfrom the juncture between it and outlet 27. Conduit 28 is termed common"since it is required for proper cooperation of valves V and H and isessentially part of each. (It is to be remarked that, unlike theremainder of FIG. 1, the proportions and shape of common conduit 28 andoutlet 27 are exaggerated for clarity.)

In the horizontal, the heavy line 29 is intended to represent the locusof the lowest points in the interiors of portion between seat 3 andoutlet 27. In this position, any liquid in the corresponding area drainsinto the outlet 27. The line 29 also emphasizes the locus of the lowestpoints of seat 3. Where the two loci meet, at point 30, the disc 6 andseat 3 will be so constructed that all points around the seat 3,corresponding to point 30, will be seated so as to leave no crevice.Preferably, in situ in diversion valve service, valve H is tiltedslightly so that line 29 as the whole slopes downward to the left.

Gland portion 10 is not self-draining, strictly speaking, but stemclearance therein will be sufficiently small as to be tolerated bysanitary regulations. It will. be evident then that all significantquantities of liquid can drain by gravity out of the interior of portion8 and the interior of portion 2 to the left of seat 4, into the drainagechamber provided by conduit 28.

The showing of valve V is in all respects similar to valve H, save forits orientation (and for such motor details as were revealed by thebreaking away ofa cover or casing member 31 of valve H). For purposes ofexplanation, each reference numeral used for a valve V part like a valveH part is the reference numeral of the latter part, but with addedthereto. Thus, in valve V, reference numeral identifies an inlet whichstructurally corresponds to inlet 25, each being but a short piece ofcylindrical pipe, the one connected to the interior of portion 2, valveH, and the other being similarly connected to portion 102, valve V,portion 102 corresponding to portion 2, valve H. Reference numeral 127of valve V is an outlet corresponding to outlet 27, and like itscounterpart 26, the element denoted by reference numeral 126, is also anoutlet. lt will be recognized that the inlet-outlet terminology has todo with the coaction of the various flow passages in flow diversionservice, rather than structural difference.

In flow diverting position, the valves 22 and 122 allow the discs 6 and106 to be seated in their respective seats 3 and 103. At this time, milkwhich has not been properly pasteurized is flowing into inlet 25 and outof outlet 26, say, to a reservoir, the contents of which will eventuallybe subjected to the pasteurization process again. In the meantime, thepasteurizing apparatus will be adjusted, by suitable control apparatus(not shown), to make it produce properly pasteurized milk.

When such adjustment is accomplished, properly pasteurized milk will beentering the interior of chamber 2, and flushing from every surfacetherein all traces of improperly pasteurized milk out through outlet 26.

It will be noted that as long as no leakage is to be observed comingfrom outlet 126 (while the valve H is diverting), valves 22 and 122 maybe operated to the FIG. IA condition with confidence that no improperlypasteurized milk has contacted valve parts between seats 3 and 103.Normally, diversion is caused to occur when the milk at a point upstreamfrom inlet 25 reaches a temperature below the legal value. that is, thevalue to which all forward" flow milk must have been subjected.Accordingly, below-level temperature milk does not actually enter inlet25 until disc 6 is seated in seat 3. On the other hand, disc 6 is notcaused to move off seat 3 until legaltemperature milk has entered thevalve and flushed chamber 2 out through outlet 26. On the other hand,since valves V and H can be operated independently of one another, it isalso possible to flush or clean parts of the system in isolation fromanother. For instance, valve V could be held in forward flow preventingcondition shown, while valve H is held in the diversion flow preventingcondition and flushed or cleaned by flow entering via inlet 25. Inpassing, it is to be remarked that liquid is ordinarily introduced intothe valves by pumps.

In any event, after forward flow has been restored, milk enters inlet 25and exists via outlet 27, enters portion 102 via inlet 125 and exits viaoutlet 127 to suitable apparatus connected thereto, designed to receiveor further process properly pasteurized milk. Should improperpasteurization occur again, valve I22 will be set to its FIG. 1 state tostop flow of milk through valve V to the last-mentioned apparatus, andvalve 22 will be put in its FIG. 1 state to diven improperly pasteurizedmilk to such apparatus as is connected to the out let 26.

The flow diversion valve arrangement of FIG. I is not onlyself-draining, but unlike its prior art predecessors, peculiarly suitedto cleaning in place, that is, without removing it from the system inwhich it is connected, and without disassembly. In these respects, flowdiversion valves must conform to various legal requirements to insurefreedom of contamination of pasteruized product and maintenance ofsanitary conditions in the parts of the valves contacted by suchproduct. One of the standards is isolation of pasteurized product fromunpasteurized product. In FIG. 1, this is insured by the self-draininginternal volume of valve between discs 6 and 106. Another requirement isleak detection, often provided by so-called leak detectors, as disclosedin the cited Karst and Hartman patents, but provided, in the presentinvention by the aforesaid internal volume of valve. Thus, in FIG. I,leakage past disc 6 drains out freely via outlet 126.

Again, to be cleanable in place, the interior of the valve must bereachable at all points by cleaning liquid. Leak detection 'as providedby the leak detector elements of Karst and Hartman makes their diversionvalves inferior to the present invention in this respect, since it isreally necessary to disassemble these prior diversion valves in order tobe able to properly clean the diversion valves.

Preferably, valves V and H are more integrated structurally than shownin FIG. 1, as shown in FIGS. 2, 3 and 5, for example. In essence, inthese latter FIGS. the common conduit 28' has been reduced to theoutlets 27' and 125', (reference numerals of FIGS. 2, 3 and 5 indicatethe same structure as in FIG. I, but are primed for purposes ofdistinction therefrom). Outlets 27 and 125' are short pieces ofcylindrical pipe welded together as at line 32. As the inclination ofline 32 indicates, the ends of the pipe would be more oval rather thancircular, hence, care should be taken that lack of congruence betweenthe ends does not leave a step or crevice at the weld. The cylinder axesof these outlets also are tilted with respect to the horizontal in whichthe axis of valve H is placed (the axis of valve V being placed in thevertical, of course). The tilt is somewhat exaggerated, and preferablyit and the dimensions of the valves are such that the level ofthe topface of disc 106 (as shown in dashed line, FIG. 3) should be above thehighest point inside portion 2' of valve H.

It will be noted, too, that outlet 27' drains away on a slant from thelowest part of portion 8' (indicated at 33, FIG. 3) rather than more orless directly down from the portion, as FIG. 1 portrays it doing.

As will be seen from FIG. 2. the discs 6' and 7 are parts ofa one-pieceplug 5' the contours of which are such as to be selfdraining. Annulargaskets, like that shown at 34 and 35, and made of a suitable sealingmaterial, such as rubber, etc., are bonded, as by vulcanizing to thebeveled portions of the discs. The interiors of the valves are generallyrounded, except that the lesser-diameter regions of the seats may mergewith inner valve surfaces, as shown in the case of seat 3', and theportion 8', along a sharp line, as portrayed at 36.

Stem 9' passes through a passage 39 in stuffing box I0 to, say, amechanical coupling (not shown). The liquid seal around the stem isfurnished solely by an O-ring 38 located in the circumferential groove40 of stem 9'. The clearance between the stem 9' and the passage 39 israther slight, thereby providing a relatively inaccessible crevice aboutthe valve stem. However, under the usual sanitary regulations, this isnot considered to detract from the self-draining and cleanabilityproperties of a valve.

In order to prevent galling or serious wear of the bearing surfaces ofstem 9' and passage 39, the bearing surface of stem 9 is hard-chromeplated, O-ring 38 merely providing a liquid seal, and guiding supportfor the stem being provided by a guide 45 (and, in the case of valve H,the side of passage 39). The guide 45, which is the form of a ring, hasa passage 46 therethrough which snugly fits stem 9'and is preferablymade of a strong, durable plastic, such as Teflon, having antifrictionproperties. Guide 45 is recessed fixedly in place in stuffing boxportion 10', and in order to provide leak detection (should 0- ring 38fail) has channels 47 arranged around the inner periphery of the guide45. Liquid leaking past O-ring 38 will flow through channels 47 to theexterior of the valve where it will be seen. (The structure whichattaches the valve motor (not shown) to the stuffing box portion 10' isordinarily open, exposing the emerging stem 9 to view from the exterior.

Lesser variations of the orientation of valves V and H, and V andH'would involve interchanging divert and leak detection outlets. Thus,the common conduit 28 (or inlets 125 and 125) could be extended up tooutlets 26 and 26 instead of to outlet 27 or 27'. Since the divertoutlet would now be outlet 27, FIG. 1A would show the divert setting ofvalve 22, unless the motor 13 were replaced by a reverse acting motor.This variant may be further varied by inverting valve V and slopingconduit 28 (or inlets 125 and 125) up to outlet 26 or 26'. This wouldmake outlet 126 or 126' the forward outlet and outlet 127 or 127 theleak detector outlet. In this second variant, either both motors l3 and113 would be replaced by reverseacting motors, or otherwise. FIG. 1Awould now show the divert condition of the valves, and FIG. 1 theforward configuration. The versions of valve orientation and connectionsshown in FIGS. 1, 2 and 3 are to be preferred, (particularly the latter,which is the most compact). It is also preferable to avoidreverse-acting motors, and operating the valve V or V in the invertedposition would permit leakage from the stuffing box section to fall onthe motor portions of the valve.

Various forms of means for connecting diversion valves with the pipingofa pasteurization system are met with in practice, hence, no particularform of outlet and inlet ends has been specified. in general, it isdesirable to seal such connections with gaskets so located and shaped asnot to provide milk-catching crevices.

Similar precautions must be taken in the valve assembly. For example, agasket 41, FIG. 3, proportioned so as to be compressed and to have itsinner periphery substantially flush with adjacent interior surfaces ofthe valve, when the faces of flanges 42 of the portions 8 and 2' are incontact as shown in FIG. 2, provides for sealing as well as cleanabilityand self drainability, in acceptable fashion.

In pasteurizing service, the valve parts contacted by milk would be madeof stainless steel, satin finished (120 grit, for example) and proofagainst attack by the cleaning and sterilizing agents customarily used.While dimensions and external form may vary, it is desirable toproportion the interior for free flow. For example, in pasteurizationservice, internal diameters may be about 2 inches (except for theplug-containing portions which would have about 3-inch inner diameters),with valve stem motion of about three-fourths inch from seat to seat.

In explaining the use and operation of the valve according to theinvention manually-controlled pneumatic valve motors have beenspecified. However, it is obvious that electrical or hydraulic motorscould be used, and that provisions for automatic control may be made.For example, in pasteurizing service, ordinarily some means formeasuring the temperature of incoming milk is provided whichautomatically causes the valve to divert if the milk drops below acertain temperature. Those skilled in the art will be aware of how toutilize our in vention in a variety of systems, without departing fromthe scope of the claims appended hereto.

We claim:

1. [n a three outlet, one inlet diversion valve having a duct; a firstseat in said duct through which one outlet opens into said duct, asecond seat through which the second outlet opens into said duct, afirst plug in said duct, said first plug being adapted to be moved fromseating on one said seat to seating on the other said seat, and viceversa; a third seat through which the third outlet opens into said duct,a fourth seat in said duct, a second plug in said duct, said second plugbeing adapted to be moved from seating on one of the two last-said seatsto the seating on the other thereof, and vice versa; said plugs, seats,outlets, and inlet being constructed and arranged such as to besubstantially self-draining while said valve remains in situ in a liquiddistribution system; the improvement wherein the spatial orientation ofsaid fourth seat, of one of said first and second seats, and of saidduct is such that, when said valve is in situ as aforesaid, said fourthseat drains by gravity through said duct and said duct drains by gravityto said one of said first and second seats, the nether portion of saidduct defining a liquid flow path sloping monotonically downward, fromsaid fourth seat to said one of said first and second seats.

2. The invention of claim 1, wherein said improvement includes saidthird and fourth seats being spatially oriented when said valve is insitu as aforesaid, such that ifliquid flowed between said third andfourth seats, such flow would be in a substantially horizontaldirection.

3. The invention of claim 2, wherein said second plug is pro vided witha stem for moving said second plug between said third and fourth seats,said stem being movable along the horizontal, and extending along thehorizontal to the region outside of said duct.

4. The invention of claim 2, wherein said first and second seats arespatially oriented, when said valve is in situ as aforesaid, such thatif liquid flowed between said first and second seats, such flow would bein substantially vertical direction.

5. The invention of claim 4, wherein said second plug is provided with astem for moving said second plug between said third and fourth seats,said stem being movable along the horizontal and extending along thehorizontal to the region outside said duct; said first plug also beingprovided with a stem, the last said stem being movable along thevertical and extending along the vertical to the region outside saidduct.

6. A liquid treating system including the valve of claim 1, and furtherincluding means arranged to cause treated liquid to enter said duct viasaid inlet, and to exit the valve from one or another of said outletswhen a said plug is not seated on the corresponding one of said seats;said one of said first and second outlets being connected to first meansfor receiving liquid and the other thereof being connected to secondmeans for receiving liquid, and said third outlet being connected tothird means for receiving liquid; said valve being in situ, asaforesaid, in said system.

7. A liquid treating system including the valve of claim2, and furtherincluding means arranged to cause treated liquid to enter said duct viasaid inlet, and to exit the valve from one or another of said outletswhen a said plug is not seated on the corresponding one of said seats;said one of said first and second outlets being connected to first meansfor receiving liquid and the other thereof being connected to secondmeans for receiving liquid, and said third outlet being connected tothird means for receiving liquid; said valve being in situ, asaforesaid, in said system.

8. A liquid treating system including the valve of claim 3, and furtherincluding means arranged to cause treated liquid to enter said duct viasaid inlet, and to exit the valve from one or another ofsaid outletswhen a said plug is not seated on the corresponding one of said seats;said one of said first and second outlets being connected to first meansfor receiving liquid and the other thereof being connected to secondmeans for receiving liquid, and said third outlet being connected tothird means for receiving liquid; said valve being in situ, asaforesaid, in said system.

9. A liquid treating system including the valve of claim 4, and furtherincluding means arranged to cause treated liquid to enter said duct viasaid inlet, and to exit the valve from one or another of said outletswhen a said plug is not seated on the corresponding one of said seats;said one of said first and second outlets being connected to first meansfor receiving liquid and the other thereof being connected to secondmeans for receiving liquid, and said third outlet being connected tothird means for receiving liquid, said valve being in situ, asaforesaid, in said system.

10. A liquid treating system including the valve of claim 5, and furtherincluding means arranged to cause treated liquid to enter said duct viasaid inlet, and to exit the valve from one or another of said outletswhen a said plug is not seated on the corresponding one of said seats;said one of said first and second outlets being connected to first meansfor receiving liquid and the other thereof being connected to secondmeans for receiving liquid, and said third outlet being connected tothird means for receiving liquid; said valve being in situ, asaforesaid, in said system.

11. A diversion valve having a drainage chamber, a horizontal flowpassage and a vertical flow passage, said chamber connecting to one endof said horizontal flow passage and to an intermediate portion of saidvertical flow passage; the lower end of said vertical flow passageterminating in an outlet, and the side of an intermediate portion ofsaid horizontal flow passage having an intake; a first plug in the firstsaid intermediate portion and a second plug in the second saidintermediate portion; said first plug being operable to allow flow fromsaid first said intermediate portion to said lower end of said verticalflow passage and to prevent flow therefrom to the other end of saidvertical fiow passage, and vice versa; said second plug being operableto allow flow from said second said intermediate portion to said one endof said horizontal flow passage and to prevent flow therefrom to theother end of said horizontal flow passage, and vice versa; said firstsaid intermediate portion being located at a lower level than saidsecond said intermediate portion, and said chamber sloping monotonicallyupward from its connection to said first said intermediate portion, toits connection to the said one end of said horizontal flow passage.

12. In the invention of claim 11, a stuffing box at one end of the saidhorizontal flow passage, and a stem extending through said stuffing boxinto the said second intermediate portion, said second plug beingsecured to said stem for operation thereby, said stuffing box having ahorizontal passage substantially filled by said stem, thereby beingmeans resiliently slidably sealing said stem in the last said passage,the outer end of said last said passage having a fluid-pervious guidesnugly and slidably grasping said stern, said stern being hardened andsmooth, for sliding thereofon the side of said last said passagev 13. Ina valve having a flow passage, a plug received between a pair of seatsin an intermediate portion of said flow passage, a stuffing box at oneend of the said flow passage, and a stem extending though said stuffingbox into the said first intermediate portion, said plug being secured tosaid stern for operation thereby, said stuffing box having a passagesubstantially filled by said stem, and there being means resilientlyslidably sealing said stem in the last said passage; the improvementwherein the outer end of said last said passage has a fluid-perviousguide snugly and slidably grasping said stem, and said stem is hardenedand smooth, for sliding thereof on the side of said last said passage.

14. In a diversion valve having a pair of cylindrical body portions,said portions being spatially oriented so that the axis of one thereofis perpendicular to the other thereof, a common duct connecting saidportions, one end of said duct being cylindrical and projecting from onesaid body portion at right angles to the axis of the latter and theother end of said duct being cylindrical and projecting from the othersaid body portion at right angles to the axis of the latter, said ducthaving its length comprising two cylindrical parts of which therespective axes are the axes ofits said end portions; each said portionhaving a plug therein movable to prevent liquid from entering said duct,via the last said portion; each said portion having a pair of seatstherein spaced along its said axis, and its said plug being movable fromone ofits said seats to the other; each said portion also having thecorresponding one of said cylindrical parts opening into it between itssaid seats.

15. The invention of claim 14, wherein the one said cylindrical partterminates in an oval end contour and the other said cylindrical partterminates in an oval end contour, said body portions being orientedwith respect to each other such that contours are substantiallycoincident, there being means securing said contours hermeticallytogether.

16. The invention of claim 14, wherein the said axis of the one saidbody portion intersects the said axis of the corresponding said end ofsaid duct, and the said axis of the other said body portion intersectsthe said axis of the corresponding said end of said duct.

17, A liquid flow system including a valve having the said body portionsof claim 14, wherein said body portions are arranged such that liquidfrom said system enters said body portions, said body portions beingspatially oriented so that the axis of said one end of said duct ishorizontal, so that the axis of the other said body portion is verticaland higher than the said, axis of said one end of said duct, and so thatone end of a diameter of said one end of said duct is at the same levelas the lowest point in said other said body portion,

